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    <title>Document</title>
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    <script>
        // 写一个函数 求m-n之间数字的和？
        function total(m, n) {
            var b = 0;
            if (m - n >= 0) {
                for (var a = n; a <= m; a++) {
                    b += a;
                }
            } else if (m - n < 0) {
                for (var a = m; a <= n; a++) {
                    b += a;
                }
            } else {
                console.log("输入错误")

            }
            console.log(b);
        }
        total();
    </script>
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